Product Overview
National Semiconductor LM3876T Overture Series 56W Audio Amplifier IC - TO-220-11 Through-Hole, NOS
Condition
Unused NOS. Markings legible: NS logo, LM3876T, date code 44AB. Leads straight, no bends or corrosion. Sourced from an electronics distributor consolidating inventory.
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Product Overview
National Semiconductor LM3876T - a 56W continuous average audio power amplifier IC from the Overture series, in an 11-lead TO-220 through-hole package. Delivers high-fidelity output with 0.06% THD+N (20Hz to 20kHz at 40W into 8Ω) and a signal-to-noise ratio of 95 dB minimum. Built-in SPiKe protection guards against overvoltage, undervoltage, thermal overloads, and instantaneous temperature peaks. Includes a hardware mute function. Now produced under Texas Instruments following the National Semiconductor acquisition.
Key Features
- 56W continuous average output power into 8Ω
- Supply voltage range: 24V to 84V total (±12V to ±42V dual-rail)
- THD+N: 0.06% at 40W into 8Ω, 20Hz to 20kHz
- Signal-to-noise ratio: ≥95 dB minimum
- Hardware mute function
- SPiKe protection: overvoltage, undervoltage, thermal runaway, instantaneous temperature peaks
- Package: 11-lead TO-220 staggered through-hole (non-isolated; metal tab connected to V-)
- Date code 44AB visible on body
Applications
- Building a gainclone amplifier from scratch - soldering the LM3876T onto a custom PCB, wiring the dual-rail supply, and listening to the result against a commercial integrated amp
- Desoldering a failed amp IC from a vintage hi-fi receiver or studio monitor and dropping this NOS unit in to restore original output
- Designing a powered speaker module where the mute function handles standby switching and SPiKe protection keeps the drivers safe during startup transients
- DIY audio projects where low distortion and a high SNR matter - home theater channel amplifiers, desktop near-field monitors, subwoofer plate amps
- Makers building custom audio hardware who want a single IC to handle amplification rather than designing a discrete output stage
Frequently Asked Questions
What power supply does the LM3876T require?
A dual-rail DC supply within the 24V to 84V total range - for example, ±12V to ±42V. Single-supply operation requires circuit modifications to create a virtual ground. The supply must be capable of delivering adequate current at the chosen rail voltage.
What is the difference between the LM3876T and the LM3876TF?
The LM3876T (this unit) is the non-isolated package. The metal tab is internally connected to the negative supply rail (V-). Mounting to a heatsink or chassis requires an insulating mica washer or equivalent to avoid a live chassis. The LM3876TF uses an overmolded plastic back for electrical isolation, simplifying heatsink mounting.
What speaker impedance does the LM3876T support?
Rated into 8Ω for the 56W continuous average specification. The IC can drive 4Ω loads with appropriate circuit design and thermal management, but power dissipation increases and protection circuitry is more likely to engage.
Does a heatsink come with this part?
No heatsink included. The TO-220 package requires an external heatsink for thermal management. The metal tab is the thermal path to the heatsink and is connected to V-, so insulation is needed when mounting to a grounded chassis.
Is this the same part as the LM3876T/NOPB?
The LM3876T/NOPB designation identifies a lead-free, RoHS-compliant version of the same device. Whether this specific unit carries that designation is not confirmed from the markings present.
The gainclone community has been chasing clean, low-part-count amplifier designs for decades, and the LM3876T keeps showing up at the center of the best ones. NOS date code 44AB - your build starts here.
